SwiftExtract: extract AccessLevelMode into SwiftExtractConfigurationShared

Reviewer asked: "why does swift-java need to map at all, can it not use
this exact enum?" — yes, after introducing a small shared target.

`SwiftJavaConfigurationShared` is intentionally lightweight (stdlib +
Foundation only): it must be symlinked into each plugin's source tree
because SwiftPM plugins can't have target dependencies. Pulling
SwiftSyntax in via `SwiftExtract` would balloon plugin builds.

Instead, introduce a sibling `SwiftExtractConfigurationShared` target
that holds nothing but the small `AccessLevelMode` enum. Both
`SwiftExtract` and `SwiftJavaConfigurationShared` depend on it; the
plugin symlink discipline (`Plugins/PluginsShared/SwiftExtractConfigurationShared`)
mirrors the existing `SwiftJavaConfigurationShared` symlink.

Effects:

- `AccessLevelMode` is the single, shared enum. swift-java's
  `Configuration` uses it directly via `@_exported import`, retiring
  `JExtractMinimumAccessLevelMode` and the four-line mapping switch
  in `Configuration+SwiftExtract.swift` (now an identity passthrough).

- `SwiftJavaConfigurationShared/Configuration.swift` guards the import
  with `#if canImport(SwiftExtractConfigurationShared)` so plugin
  builds (which inline the file alongside `AccessLevelMode.swift` via
  symlink rather than as a separate module) still compile.

- `AccessLevelMode` gains `@nonexhaustive` (SE-0487, gated with
  `#if compiler(>=6.2)`) per reviewer request, so adding cases in
  the future is non-breaking. `Codable` conformance is added so it
  can replace `JExtractMinimumAccessLevelMode` in the on-disk
  `Configuration` JSON without changing the wire format.

- The CLI's `@Option var minimumInputAccessLevelMode` and the
  `ExpressibleByArgument` conformance switch over to
  `AccessLevelMode` accordingly.

Author: ktoso

Package.swift

@@ -43,6 +43,11 @@ let package = Package(
       targets: ["SwiftJavaConfigurationShared"]
     ),
 
+    .library(
+      name: "SwiftExtractConfigurationShared",
+      targets: ["SwiftExtractConfigurationShared"]
+    ),
+
     .library(
       name: "JavaUtil",
       targets: ["JavaUtil"]
@@ -276,7 +281,14 @@ let package = Package(
     ),
 
     .target(
-      name: "SwiftJavaConfigurationShared"
+      name: "SwiftJavaConfigurationShared",
+      dependencies: [
+        "SwiftExtractConfigurationShared"
+      ]
+    ),
+
+    .target(
+      name: "SwiftExtractConfigurationShared"
     ),
 
     .target(
@@ -351,6 +363,7 @@ let package = Package(
         .product(name: "SwiftSyntax", package: "swift-syntax"),
         .product(name: "SwiftSyntaxBuilder", package: "swift-syntax"),
         .product(name: "Logging", package: "swift-log"),
+        "SwiftExtractConfigurationShared",
       ],
       path: "Sources/SwiftExtract",
       resources: [

Plugins/PluginsShared/SwiftExtractConfigurationShared

@@ -0,0 +1 @@
+../../Sources/SwiftExtractConfigurationShared

Sources/JExtractSwiftLib/Configuration+SwiftExtract.swift

@@ -18,16 +18,14 @@ import SwiftJavaConfigurationShared
 /// Bridges swift-java's `Configuration` onto the language-neutral
 /// `SwiftExtractConfiguration` surface consumed by `SwiftExtract`.
 ///
-/// Most members are satisfied directly by `Configuration`'s own properties; only
-/// the two enum-typed members need a mapping from swift-java's enums onto the
-/// neutral `AccessLevelMode` / `Logger.Level`.
+/// Most members are satisfied directly by `Configuration`'s own properties.
+/// `Configuration` shares `AccessLevelMode` with the analyzer (both pull it in
+/// from `SwiftExtractConfigurationShared`), so `swiftExtractAccessLevel` is a
+/// straight passthrough. Only `swiftExtractLogLevel` needs a mapping from
+/// swift-java's `LogLevel` onto the neutral `Logger.Level`.
 extension Configuration: SwiftExtractConfiguration {
   public var swiftExtractAccessLevel: AccessLevelMode {
-    switch effectiveMinimumInputAccessLevelMode {
-    case .public: .public
-    case .package: .package
-    case .internal: .internal
-    }
+    effectiveMinimumInputAccessLevelMode
   }
 
   public var swiftExtractLogLevel: SwiftExtract.Logger.Level? {

Sources/SwiftExtract/SwiftExtractConfiguration.swift

@@ -12,16 +12,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-/// Minimum access level a declaration must have to be considered for extraction.
-///
-/// Language-neutral counterpart to a configuration's access-level setting. The
-/// concrete `Configuration` types in language layers (e.g. swift-java, or other
-/// language code generators) map their own enums onto this.
-public enum AccessLevelMode: String, Sendable {
-  case `public`
-  case `package`
-  case `internal`
-}
+@_exported import SwiftExtractConfigurationShared
 
 /// The configuration surface required by the language-neutral `SwiftExtract`
 /// analysis layer.
@@ -33,9 +24,14 @@ public enum AccessLevelMode: String, Sendable {
 /// (e.g. Java/JNI/FFM, or other language code generators) without pulling
 /// target-specific config types into `SwiftExtract`.
 ///
-/// The two enum-typed members use `swiftExtract`-prefixed names so a conforming
-/// type can keep its own, differently-typed `logLevel` /
-/// `effectiveMinimumInputAccessLevelMode` members without a name collision.
+/// `AccessLevelMode` lives in the small `SwiftExtractConfigurationShared`
+/// target so language-specific configuration shared modules (e.g.
+/// `SwiftJavaConfigurationShared`) can use the same enum directly without
+/// taking a dependency on SwiftSyntax.
+///
+/// The enum-typed `swiftExtractLogLevel` member uses a `swiftExtract`-prefixed
+/// name so a conforming type can keep its own, differently-typed `logLevel`
+/// member without a name collision.
 public protocol SwiftExtractConfiguration {
   /// Name of the Swift module being analyzed.
   var swiftModule: String? { get }

Sources/SwiftExtractConfigurationShared/AccessLevelMode.swift

@@ -0,0 +1,34 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024-2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+/// Minimum access level a declaration must have to be considered for extraction.
+///
+/// Lives in the small `SwiftExtractConfigurationShared` target so the analysis
+/// layer and language-specific configuration layers (e.g. swift-java's
+/// `SwiftJavaConfigurationShared`) can both depend on it without dragging
+/// SwiftSyntax into the latter.
+#if compiler(>=6.2)
+@nonexhaustive
+#endif
+public enum AccessLevelMode: String, Codable, Sendable {
+  case `public`
+  case `package`
+  case `internal`
+}
+
+extension AccessLevelMode {
+  public static var `default`: Self {
+    .public
+  }
+}

Sources/SwiftJavaConfigurationShared/Configuration.swift

@@ -14,6 +14,13 @@
 
 import Foundation
 
+// In a real module build this resolves to a separate target. In plugin builds
+// the file is inlined (via symlink) alongside `AccessLevelMode.swift`, so the
+// module isn't a discoverable import — guard with canImport.
+#if canImport(SwiftExtractConfigurationShared)
+@_exported import SwiftExtractConfigurationShared
+#endif
+
 ////////////////////////////////////////////////////////////////////////////////
 // This file is only supposed to be edited in `Shared/` and must be symlinked //
 // from everywhere else! We cannot share dependencies with or between plugins //
@@ -62,8 +69,8 @@ public struct Configuration: Codable {
     writeEmptyFiles ?? false
   }
 
-  public var minimumInputAccessLevelMode: JExtractMinimumAccessLevelMode?
-  public var effectiveMinimumInputAccessLevelMode: JExtractMinimumAccessLevelMode {
+  public var minimumInputAccessLevelMode: AccessLevelMode?
+  public var effectiveMinimumInputAccessLevelMode: AccessLevelMode {
     minimumInputAccessLevelMode ?? .default
   }
 

Sources/SwiftJavaConfigurationShared/JExtract/JExtractMinimumAccessLevelMode.swift

@@ -66,7 +66,7 @@ extension SwiftJava {
     var writeEmptyFiles: Bool?
 
     @Option(help: "The lowest access level of Swift declarations that should be extracted, defaults to 'public'.")
-    var minimumInputAccessLevelMode: JExtractMinimumAccessLevelMode?
+    var minimumInputAccessLevelMode: AccessLevelMode?
 
     @Option(
       help:
@@ -222,6 +222,6 @@ struct IllegalModeCombinationError: Error {
 }
 
 extension JExtractGenerationMode: ExpressibleByArgument {}
-extension JExtractMinimumAccessLevelMode: ExpressibleByArgument {}
+extension AccessLevelMode: ExpressibleByArgument {}
 extension JExtractMemoryManagementMode: ExpressibleByArgument {}
 extension JExtractAsyncFuncMode: ExpressibleByArgument {}